Impact ram



jam, 316, 11968 J. B. OTTESTAD IMPACT RAM 6 Sheets-Sheet 1 Filed July11, 1966 INVENTOR.

Jan. 16, 1968 J. B OTTESTAD IMPACT RAM 6 Sheets-Sheet 3 Filed July ll,1966 INVENTOR. J CK 5. 0771557770 ATTORNEVS Jan. 16, 1968 J. B. OTTESTAD3,36

IMPACT RAM Filed July 11, 1966 Pia/3 r 4 M 6 Sheets-Sheet 4 /4 /2 15F/G./5 -A I 7 INVENTOR. v JACK a. arm-$7140 A TTORNEYS.

Jan. 16, 1968 J, OTTESTAD 3,363,513

IMPACT RAM Filed July 11, 1966 6 Sheets-Sheet 5 lga /28 IN VENTOR. JACK5. 07755740 ATTORNEYS.

Jan. 16, 1968 J. B. OTTESTAD 3,363,513

IMPACT RAM Filed July 11, 1966 6 Sheets-Sheet 6 INVENTOR. ACK 8.OT'T'FSTAP A? ATTORNEY-.5. V

United States Patent T 3,363,513 IMPACT RAM Jack B. Ottestad, 1442Muirlauds Drive, La Jolla, Calif. 92037 Continuation-impart ofapplication Ser. No. 476,383,

Aug. 2, 1965. This application July 11, 1966, Ser. No. 564,320

16 Claims. (Cl. 91-5) ABSTRACT OF THE DISCLOSURE This invention relatesto an impact ram wherein a body has an internal plunger, which plungeris adapted to be axially driven relative to the body in order to delivera blow. Means is provided for quickly impacting on the face of theplunger, energy which is stored in' a chamber in preparation forrendering said blow.

This is a continuation-in-part of applicants co-pending patentapplication, Ser. No. 476,383, filed Aug. 2, 1965, entitled, Impact Ram,now abandoned.

This invention relates to fluid-powered impact rams.

Devices for striking bodies or surfaces are widely known. Theirobjective is to impart to the body or surface a quantity of energy in arelatively short time. The energy is usually derived from propelled orfreely falling weights, from powered linkages, from the quick release ofa fluid stored under pressure, or from an explosion. The field ofmechanisms powered by quick release of a fluid stored under pressure hasbeen the subject of much development, which development has beencharacterized by a steady increase in the complexity of the devices. Itis an object of this invention to provide an impact means which utilizesa minimum of parts which parts are easily and inexpensively manufactured'and assembled.

It is another characteristic of conventional impact rams that theirenergy output is not readily adjustable so that blows of greater orlesser energy can be produced. This invention provides for readyselectivity of the energy level from blow to blow.

A very serious deficiency inherent in conventional fluid-powered devicesis the risk of misfire when attempting to unload them after the deviceis charged or cocked." Occasionally it is necessary, after charging themachine, to release the energy 'but without causing the machine toundergo a work-cycle. This has been difficult, and sometimes evenimpossible, to arrange for in previously-known machines, and thesemachines, when once charged, remain a potential danger to theiroperators until after a work stroke is completed which discharges theenergy. The same problem arises when the energy of the charge is onlypartially discharged. This invention provides a safe, fluid-poweredimpact device which can always safely and quickly be unloaded withoutundergoing a work cycle.

Another serious problem in conventional devices occurs when the devicefires, but fails to strike a workpiece which would receive the energy.Then the traveling parts of the machine would continue in rapid motion,and serious damage to the machine is likely to result. The disadvantageand danger of such a situation is .obvious, for were the machine tomisfire, or fire when for some reason there were no workpiece inposition (both of these being possibilities in routine factoryoperations), then serious damage is done to expensive capital equipment.This invention provides means which inherently decelerates therapidly-moving parts toward the end of a stroke, so that the device isfully protected against damage from this cause.

3,363,513 Patented Jan. 16, 1968 Still another disadvantage ofpresently-known impact rams is the fact that their deceleration beginsat a specific point in their stroke, rather than along a substantiallength. An optimum blow will be delivered only at one specific locationin the axial travel, and should the blow be delivered elsewhere, then aless than optimum blow will be de livered.

It is an object of this invention to provide a coasting feature toenable an optimum blow to be delivered over an extended axial range.

It is a further object of this invention to provide a valve which willautomatically cycle the ram.

It is still another object of this invention to provide a device which,while useful for impacting objects, can also provide a steady force toact as an arbor press, for example, or to oscillate thereby to providevibrational energy.

An impact ram according to this invention includes a body having aninternal body cylinder extending along the axis of. motion. The cylinderis closed at a first end of the body andopen at a second end. A plungeris axially slidable in the body cylinder, and is adapted to be connectedto an object, an example being an impact head for use as a hammer, whichobject is disposed outside the body. The plunger or means projectsthrough the open second end of the body cylinder.

The plunger has a lateral dimension which is less than a correspondinginternal lateral dimension of the body cylinder. The plunger carries acollar which makes a continuous peripheral fluid-sealing contact withthe inside wall of the 'body cylinder. A sliding seal disposed betweenthe plunger and the body forms one boundary of a variable volume returnchamber, the other boundaries of which are an inner wall of the body,the collar, the inner wall of the body cylinder, and the exteriorsurface of the plunger which has said lesser lateral dimension.

A return face is disposed on the collar which faces into the said returnchamber. Fuild pressure in the return chamber tends to return theplunger axially toward the first end of the body. A triggering surfaceon the collar faces the closed end of the cylinder.

A plunger cylinder extends axially in the plunger. A piston axiallyfloats in the plunger cylinder. The piston makes a fluid-sealing slidingfit with the inner. Wall of the plunger cylinder. The plunger cylinderis open at its ends facing the said first end of the body cylinder andis closed at its other end. The piston forms an accumulator chamber ofvariable volume between itself and the closed end of the plungercylinder.

A peripheral charging seal includes a surface on the plunger that isdisposed laterally of the triggering surface,

and a complementary surface on the body inside the cylinder. When thesesurfaces mate to form a seal, there is an axial spacing which forms atriggering chamber between the trigger surface and the body. Thetriggering chamber, when the elements of the device are in such aposition, is fully enclosed. At this time, the piston faces the regionof the body which is inside the seal. It faces this region through theopen end of the plunger, and forms a charging chamber therein.

Respective port means is provided for admitting fluid under pressure tothe return chamber, the triggering chamber, the charging chamber, andthe accumulator chamber.

The following are preferred but optional features of the invention:

i) the device, thereby simplifying the construction of the ram.

The above and other features of the invention will be fully understoodfrom the following detailed description and the accompanying drawings inwhich:

FIG. 1 is a partial view in axial cross-section of a device according tothe invention;

FIG. 2 is a cross-section taken at line 2-2 of FIG. 1;

FIGS. 3-8 are axial cross-sections showing the device of FIG. 1 insuccessive operative positions;

FIG. 9 is a schematic showing of a second valve condition in FIG. 8;

FIG. 10 is a fragmentary view of another embodiment of the invention;

FIG. 11 is a schematic showing of a second valve condition in FIG. 10;

FIG. 12 is a fragmentary schematic view showing an alternate triggeringmeans;

FIG. 13 is an axial partial section showing a modification of the deviceof FIG. 1;

FIG. 14 is a cross-section taken at line 1414 of FIG. 13;

FIG. 15 is the same view as FIG. 13, with the device in anotheroperating position;

FIGS. 16-18 are axial partial sections showing another modification ofthe device of FIG. 1 in three operating positions;

FIG. 19 is a partial cross-section of a valve shown in FIGS. 10 and 11;and

FIGS. -22 are cross-sections taken at lines 20'20, 21-21 and 2222 ofFIG. 19, respectively.

An impact ram 10 according to the invention has an axis 11 of motion inorder that oppositely directed forces may be exerted between two objectssuch as a frame, and an object or surface to be struck or pressed. Anexample of such an object is a pin to be driven into or out of a hole.The ram includes a body 12 which encloses an axially-extending bodycylinder 13. At a first end 14, the cylinder is closed by an end cap 15that is threaded into the tubular portion 16 of the body. A peripheralsealing ring 17 seals between the tubular portion and the end cap.

At the second end of the body, there is an inwardly projecting collar 18(FIG. 3) which includes a seal 19 and a counterbore 19a for purposes yetto be described. The second end of the body is open so as to receive andmake a fluid sliding fit with a plunger 20 that is fitted into the bodycylinder.

A peripheral collar 21 is formed on the plunger, and it projectslaterally from a generally cylindrical side wall 22. It will now be seenthat a return chamber 23 of variable volume is formed between collars 18and 21, cylinder 13 and sidewall 22. Sidewall 22 has a lesser lateral(radial) dimension than the wall of cylinder 13. Return surface 24(composed of portions 24a and 24b) is formed on collar 21 and presents anet lateral area to pressure in the return chamber.

A seat insert 25 is threaded to the plunger so as to form a partthereof. This insert includes an opening 25a from an inside plungercylinder 26 to the end of the plunger adjacent to the first end of thebody cylinder.

At the end of the plunger which is adjacent to said first end, there isa peripheral surface 27 that is intended to mate with a like surface 28on the end cap. The region of collar 21 which lies radially outside ofthese surfaces when they are joined, and which faces toward the end cap,constitutes a triggering surface 29. The region between triggeringsurface 29 and the end cap, which lies radially outside of surfaces 27and 28 when they are joined, is denoted as a triggering chamber 30.

A piston 31 is slidably fitted in plunger cylinder 26. A sealing ring 32makes a fluid-sealing fit between the piston and the plunger cylinder. Astop shoulder 33- (FIG. 3) is formed in the plunger cylinder to limitthe movement of the piston to the left in FIG. 3.

Insert 25 includes a tapered surface 35.

The region between the central portion 37 of the end cap and the piston,within the plunger cylinder, is denoted as a charging chamber 38. Theregion within the plunger cylinder between its closed end and the pistonis denoted as an accumulator chamber 39.

The piston carries a seat 45 intended to form a fluidtight seal withseat 46 on insert 25 when the nose is fully to the right as illustratedin FIG. 1. In this position, there remains an annular spacing 48 betweensurface 49 on the seat insert and an opposed surface 50 on the piston.Charging ports 51 pass through tubular portion 22 of the plunger tointerconnect spacing 48 and return chamber 23. This interconnectionexists irrespective of the location of the piston in the plunger.Charging ports 51 constitute part of a fluid-supply means common tocharging chamber 38 and return chamber 23. As soon as the piston movesslightly to the left in FIG. 1, spacing 48 becomes part of the chargingchamber, and is included within the scope of the term charging chamberin all conditions.

The piston also includes an optional metering pin 50a that is adapted toenter the cylindricallywalled portion 50b of the charging chamber. Anannular clearance 500 is formed between these surfaces to enable ametering action to be attained in addition to that provided between seat45 and seat 46 when such additional metering is desired, as it usuallyis.

A residual charge of gas is injected into accumulator chamber 39 from asource 54 (see FIG. 8) through a valve 55. Valve 55 may be carried bythe plunger. Once this residual charge is injected, it is left in theaccumulator chamber, and this chamber requires no further attentionexcept for replacing gas which may leak out.

A triggering charge port 56 (FIGS. 1 and 8) passes through the end capand enters the triggering chamber. It receives pressure for triggeringthe device through conduit 61 from pressure which originated at source57, although the energy may have been stored originally in 'fiuidcommunication with conduit 62. Valve 58 has two settings. The returnsetting is shown in FIG. 8, where port 59 is connected to pressure andport 56 to exhaust. The other setting is shown in FIG. 9, where ports 56and 59 are interconnected, and the pump is by-passed to the reservoir.The valve setting of FIG. 8 causes the return of the plunger and thecharging of the device. The setting of FIG. 9 fires the device. Conduit61 connects valve 58 to the triggering charge port, and conduit 62connects valve 58 to the return charge port.

In the embodiment of FIG. 1, port 59 functions as entry for both thereturn and charging fluid, ports 51 serving as operating charge ports,in series connection with port 59. In the alternate embodiment of FIG.10, the return and charging chambers are supplied by parallel ratherthan by series circuitry. The structural difference between the twodevices is the elimination in FIG. 10 of charging ports 51 in theplunger, and the substitution therefor of charging port 52 through theend cap. Apart from this, the structures are alike. The conduitry isalso somewhat different. It includes a valve which has two conditions.The first is shown in FIG. 10, and the second in FIG. 11. In FIG. 10, apressure source 91 is connected by conduit 90a to the valve and toconduit 92 and thence to return port 59. In this setting, charging port52 is connected by conduit 93 to reservoir (exhaust) 94, all reservoirsin this invention having a lower pressure than that produced by sourcessuch as pumps 54 and 91.

The second condition of valve 90 shown in FIG. 11, wherein conduits 92and 93, and therefore both return and charging chambers, are connectedto the pressure:

source.

The first condition is for the return of the plunger. The secondcondition is for charging and firing.

FIGS. 19-22 constitute a more detailed showing of valve 90. This valveincludes a sleeve $012 with a cylindrical inner wall 90c and arotatable, closely fitting valve core 90d therein. Ports 90c and 90] areconnected to conduits 90a and 92. Port 90g is connected to conduit 93.Passage 90h includes a branch 901' at right angles. In the positionillustrated, all these ports and passages are aligned. When the core isturned 45 none is aligned.

Axially spaced from the aforesaid ports and passages are two additionalpassages (FIGS. 21 and 22) 9-0j and 90k, which are axially separatedfrom each other, and at 90 to each other. They are at 45 to passages 90kand 901'. Ports 90l and 90m are aligned and pass through the sleeve.Ports 90n and 90p are aligned and pass through the sleeve, axiallyspaced from ports 901 and 90m. None of these ports and passages is nowaligned. A rotation of 45 clockwise in FIGS. 21 and 22 will align them,and place passages 9011 and 90i out of alignment.

Port 90l connects to conduit 93a; port 90m to conduit 93; port 90n toconduit 92; and port 90p to conduit 90a.

The condition of valve 90 in FIG. 11 in shown in FIG. 11. The conditionof valve 90 in FIG. will result from a 45 clockwise rotation of core90:1 in FIGS. 20-22.

A triggering valve 95, which can be a three-way valve, is connectedbetween conduit 93 and triggering port 56. In one condition, it ventstriggering port 56 and the triggering chamber. In the other condition itadmits pressure from conduit 93.

FIG. 13 shows the presently-preferred embodiment of the invention. It isbasically the device of FIG. 1 with a delay means 110 added. Likenumbers have been used to indicate like parts. The delay means includesan extension 1:11 on seat member 25, which extends axially toward thesecond end. Port 51 continues through this extension.

A piston 112 is substituted for piston 31. It performs the same functionas piston 31, and includes the same seats. However, instead of makingonly a single step between seat 45 and the largest diameter, it makes adouble step, including a by-pass surface 113 and a metering surface 114.Radius R of surface 114 is greater than that of surface 113.

Extension 111 includes a metering surface 115 whose radius is slightlygreater than R This forms a metering, or delay, annular gap or orifice116 between the metering surfaces when they are axially aligned. Whenby-pass surface 113 and metering surface 115 are axially aligned, theannular region between them is large enough that it does not exert asignificant metering action.

A metering chamber 117 is formed between face 118 on the piston and face119 on the extension when orifice 116 is formed.

FIGS. 16-18 show a modification of the device of FIG. 1 which isself-cycling. Like numbers are used as far as possible. Cap is modifiedto include valving elements and a poppet is added to piston 31. There isno change in the remainder of the device.

Cap 125, which is substituted for cap 15, is like cap 15 except thatport 126 is simply a vent, and it enters a vent chamber 127 on theopposite side of a valve land 128 from the piston. A cycling chamber 129is disposed on the other side of valve land 128 and connected to thetriggering chamber by passage 129a. Both chambers surround a poppet 130which is attached to the nose of piston 31.

Poppet 130 includes a valve land 131 which makes a are overlapped untillands 128 and 133 are overlapped,

after which the former separate. Thus, in the position of 6 FIG. 16, thedistance from the left edge of land 132 to the right edge of land 131 isgreater than the distance from the right edge of land 128 to the leftedge of land 133.

The operation of the device of FIG. 1 as an impact ram is as follows.

Initially the accumulator chamber will be charged with its residualcharge. The pressure of this residual charge is one of the determinantsofthe energy output of the impact ram. In one device wherein thediameter of the plunger cylinder is about 3 inches, nitrogen gas, orsome other inert gas is injected into the accumulator chamber to apressure of between about 1000 p.s.i.g. and about 1500 p.s.i.g. At thistime all other regions in the device are vented to-atmosphere. Thenvalve 55 is closed. As a result of this residual charge, the piston willbe moved relative to the plunger to the location shown in FIG. 1, withthe piston firmly seated against insert 25, a seal being made betweenseats 45 and 4 6. However, a tight fluid seal is not essential, althoughit is desirable. The same is true of the other seals in these devices,because minor leakage therein does not impede the function of thedevice, -nor render it liable to misfires.

At this time, the position of the plunger in the body is indefinite.Next, valve 58 is set to the condition of FIG. 8, in order to venttriggering port 56 and supply fluid under pressure to port 59. Now fluidenters return chamber 23, and through ports 51, enters spacing 48.Because there is only exhaust pressure in opposition on the right handside of the plunger (or, if there is only a metering action, a lesserpressure on the right side,) a net pressure is exerted on the returnsurface to move the plunger fully to the right, to the position shown inFIG. 1. At this position, surfaces 27 and 28 meet and seal, andtriggering chamber 30 is fully isolated from the rest of the system.This condition is shown in FIG. 3.

Rising pressure applied in spacing 48 through ports 51 now begins toovercome the resistance of the gas acting on the piston and moves thepiston to the left. This is the start of the charging operation which isshown partially completed in FIG. 4. Pressure in the charging chamber isnow exerted over the full right hand area of the piston, the seal havingbeen broken at 45, 46 if one was initially made. The plunger is lockedin the position of FIG. 1, because of the different forces on the returnand triggering surfaces, the force on the return surface being thegreater. The residual charge in accumulator chamber 39 is compressed asthe piston moves to the left, the amount of compression beingproportional to the pressure exerted in charging chamber 38. Theretherefore exists a discrete axial position of the piston in the plungerfor each pressure level within a wide range, and the energy level can beset by adjusting the charging pressure.

If the charging pressure is great enough, the piston will be movedagainst stop 33, and there will be no further compression of theaccumulator charge. This condition is shown in FIG. 5, where the unit ischarged or cocked, and ready to fire. In the example given, a chargepressure of 2500 p.s.i.g. is often used. Energy is now stored in theaccumulator chamber, and the plunger is locked onto the body by pressureon return surface 24.

At this time it is perfectly safe to vent charging chamber 38, and theenergy will harmlessly be dissipated and the device safetied, should awork stroke not be desired. The piston would simply return to itsinitial position at the open end of the plunger. This is a veryimportant safety advantage over prior art devices.

Assuming the charge is to be used forimpact purposes, the ram may betriggered by changing valve 58 to the condition of FIG. 9, thereby toapply pressure to triggering port 56 and triggering chamber 30. Theforce in the triggering chamber will overcome the force holding the sealat surfaces 27 and 28 and move the piston axially to the left, and thetriggering and charging chambers are fully interconnected past theseparated surfaces. Now, and

quite suddenly, the charge pressure is exerted over the full area of theright-hand face of the plunger. The plunger therefore moves to the left,as shown in FIG. 6.

The movement of the plunger to the left is caused by movement of thepiston to the right (relative to the plunger), thereby exerting theenergy of the accumulator charge on the liquid in the charging chamber.The plunger expels liquid from the plunger cylinder into the bodycylinder as it moves.

Preferably, the piston will approach the end of its stroke and havetransferred the maximum energy to the plunger, by the time the plungerhas traveled between about /3 and A; of its maximum length of stroke.The device is shown approaching this condition in FIG. 6, and at thiscondition in FIG. 7. It is preferable for impact to occur at the pointshown in FIG. 7, and the impact would dissipate the energy.

However, now assume that nothing is struck by a body such as hammer 100,or that the blow is not totally absorbed. Then the plunger mustdecelerate, or the device will be damaged. The remainder of the strokeaccomplishes that deceleration, and the condition is shown in FIGS. 7and 8.

Note in FIG. 7 that, with the plunger moving left, the return chamber isdecreasing in volume. The major escape of its fluid is through conduits51. Some, but only a limited amount, will go through conduits 61 and 62.This second fiow path is not necessary, and the conduitry could berevised to eliminate it, if desired. Spacing 48 is closed by the pistonat seats 45 and 46 when the piston is all the way to the right. Thiswill cause the pressure to rise in the return chamber and in spacing 48,and this rise in pressure will shift the piston to the left to open upthe passage through the plunger at a clearnace 101. This becomes ahigh-pressure decelerating restraint on the plunger adequate fully todecelerate the plunger while still preventing fluid-lock and attendantdamage to the device by opening up in response to excessive pressures.Ports 51 are quite large in total area, and are ample to transfer theliquid from return chamber 23 to charge chamber 38 during the stroke.

Finally, the end of the stroke is reached as shown in FIG. 8, andrecycling can be done.

Counterbore 19a provides a residual chamber for return fluid, and alsokeeps port 59 from being blocked by the plunger.

To repeat the cycle, the plunger will be returned to seal at surfaces 27and 28 by introducing pressure into return chamber 23, and venting theport 56. Continuing application of pressure at port 59 will compress thecharge in accumulator chamber 39 to ready the machine for anotherstroke. Applying pressure to triggering chamber 30 initiates the stroke.

Attention is called to the fact that seals 27 and 28 are cylindrical.They need not be, but it has been found that when the device is beingcycled rapidly, for example once per second, that if laterally-extendingseals are used, they may bounce, and the device chatters and slows down.There can be no bounce between concentric cylindrical seals. Slightleakage between these seals is of no consequence, because the triggeringchamber is vented.

In the embodiment of FIG. 10, the return stroke is caused by settingvalve 95 to vent (back to reservoir), and valve 90 in the condition ofFIG. 10. To charge, valve 90 is set to the condition of FIG. 11. Tofire, valve 90 is left in the condition of FIG. 11, and triggering valve95 is set to admit pressurized fluid from conduit 93 to the triggeringchamber.

Deceleration in this case is caused by the metering effect of port 59,and also of the shoulder portions 24a and 2412 with collar 18 near theend of the stroke.

The triggering circuitry is optional in all embodiments. Instead offluid circuitry, 21 triggering pin 102 could be provided through the endcap mechanically to force the plunger off its seat with the body toinitiate the cycle. Triggering chamber 30 is not placed under pressureto trigger the device in the embodiment of FIG. 12 as it is in theembodiment of FIG. 1. In FIG. 12 a mechanical force to move the plungeraway from end cap 15 is exerted directly on the plunger by pin 102.However, in both embodiments, chamber 30 must be provided in order forthe plunger to be retained in the charged condition until it is fired,and the term triggering is used in both embodiments as a matter ofconvenience and uniformity in description even though the chamber itselfis not used for the provision of a fluid triggering force in theembodiment of FIG. 12.

The peripheral seals, cylinders and chambers are all preferably coaxialand round. The relative motions are all axial, along axis 11.

The blow-imparting operations of the device of FIGS. 13-15 are as inFIGS. l] 0. However, it will be noted that deceleration begins when thepiston has moved all the way to the open end of the plunger so thatseats 45 and 46 shut off flow from the return chamber to the chargingchamber. Delaying this closure will enable the plunger to coast. That isthe purpose of the delay means. So long as by-pass surface 113 andmetering surface are aligned, the function is as already described.However, when metering surfaces 114 and 115 are aligned, then the flowof liquid from metering chamber 117 is metered and delay by orifice 116.This delays the closing of seats 45 and 46, and fiuid continues totransfer through ports 51 from the return chamber to the chargingchamber and the plunger coasts. Finally the piston reaches the positionof FIG. 13, and deceleration begins as in FIG. I. The benefit is, ofcourse, the opportunity to strike an optimum blow at any point along asignificant axial extent.

The blow-imparting operation of the device of FIGS. 16 and 17 is as inFIGS. 1-15. The modification of FIGS. 16-18 may be utilized in any ofthem.

FIG. 16 shows the start of a cycle. Lands 131 and 132 close off thecharging chamber. Cycling chamber 129 is vented, as is the triggeringchamber, past land 128. As the device is charged, the plunger is held tothe cap and the piston moves to the left. Lands 128 and 133 join,closing the vent to passage 129a and the triggering chamber. Then land131 clears land 132 (FIG. 17). This releases pressure from the chargingchamber into the triggering chamber, through passage 129a, firing thedevice.

After firing, and during recharging, the piston returns gradually towardthe right (FIG. 18), first closing the charging chamber at lands 131 and132, and opening the cycling chamber to vent. This enables the plungerand the piston to return to the position of FIG. 16 and the cycle willrepeat.

Note that the only reversal of fiow direction is in the short passage129a, rather than in long lines. Flow through long lines isunidirectional.

When it is desired for the device to be selectable between automatic andmanual operation, then a port 56 will tap chamber 129, and a valve willbe provided to cut off chambers 127 and 129 from passage 129a, and, ifnecessary, chambers 127 and 129 connected to vent one to the other toenable the poppet to move without restriction.

In one practical device according to FIG. 13, in a total stroke of about10 inches, there are about 3 /2 inches of accelerative movement, about 3inches of coasting move ment available, and about 3 /2 inches ofdecelerative movement available.

Any suitable gas may be used where gas is called for, but preferably thegas used should be inert and inexpensive. Nitrogen is the preferred gas.Any good bydraulic fluid which will not break down under the rapid flowconditions involved herein may be used anywhere in the device whereliquid is called for.

Either embodiment of the device can also be used to apply a steadyforce, simply by venting the return chamber to reservoir and applyingpressure through the triggering port. Return motion is accomplished byreversing these connections. When this use is contemplated, then a sealshould be provided at seats 45 and 46, and this seal will remain tightat pressures in the charging chamber wherein the force against thepiston is less than that of the accumulator charge.

With this arrangement, the device can also provide a vibrational effect,for when the plunger bears against a suitable resistance and thepressure in the charging chamber rises enough to unseat the piston, thenthere will be a temporary relief of pressure in the charging chamberbecause of flow past seats 45 and 46 into the vented return chamber. Theresistant load (which might be derived from a supporting vehicle) wouldthen cause the plunger to move slightly. When the pressure is relievedenough that seats 45 and 46 again seat, then the original force on theplunger is restored, and the cycle is automatically repeated. Thiscycling can be quite rapid.

The invention provides a versatile impact ram which can be made in awide range of sizes, each of said sizes beng operable over 'a wide rangeof residual accumulator charges and charge levels in charging chamber38, which is fail safe, includes effective deceleration means, and canbe used as a standard press and as a vibrating press. Its simplicity isevident from the drawings. It requires only a minimum of parts, all ofsimple configuration, with only a minimum of critical dimensions.

It is to be noted that the accumulator charge need not be fullycompressed to operate the device. The device is as ready to operate inFIG. 4 as it is in FIG. 5. However, the energy of the blow in FIG. 4would be less than of the blow delivered from the condition of FIG. 5,assuming equal residual accumulator pressures.

This invention is not to be limited by the embodiments shown in thedrawings and descrbed in the description, which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

I claim:

1. An impact ram having an axis, comprising: a body having an internal,axially-extending body cylinder; a plunger having an internal,axially-extending plunger cylinder; a piston axially slidably fitted insaid plunger cylinder, the body and plunger, and the piston and plungerbeing relatively axially slidable; a laterally-extending collar on thebody making a substantially fluid-sealing fit with the external surfaceof the plunger, a laterally-extending collar on the plunger making asubstantially fl'uidsealing fit with the body cylinder, whereby a returnchamber of variable volume is defined by the body cylinder, the plungerand the collars; a return surface on the plunger collar facing into thereturn chamber; a triggering surface on the plunger collar facing towarda first, closed end of the body within the body cylinder; a peripheralseal carried by the body at said first end thereof inside the bodycylinder; a peripheral seal carried by the plunger at its end adjacentsaid seal on the body, the plunger cylinder having an openingcommunicating with said lastnamed seal, whereby the two said seals areadapted to make a fluid-sealing closure when the plunger is moved to itsfull extent toward said first end, said closure separating a triggeringchamber formed between the said first end and the triggering surfacewithin the body cylinder from a charging chamber formed between saidfirst end and the piston inside the plunger cylinder, the opposite endof the plunger cylinder being closed, whereby the piston forms anaccumulator chamber of variable volume, said accumulator and chargingchambers being separated from each other by the piston; an accumulatorport opening into the accumulator chamber for admitting gas underpressure thereinto; means movable with the piston for containing the gasin the accumulator chamber; conduitry opening into the body in fluidcommunication with both the return and charging chambers; valve meanscontrolling flow of fluid into and out of said conduitry; and

triggering means for moving the plunger away from said first end;whereby when fluid under pressure in the conduitry enters the returnchamber, it moves the plunger to said full extent to cause said seals toseat and then enters the charging chamber to move the piston against thegas in the accumulator chamber, and thereafter the triggering means nextare actuated to move the plunger so as to separate the seals and exertpressure of the charging chamber over the dull lateral area of theplunger, and the plunger body moves axially so as to increase thespacing between the first end of the body and the triggering surfaceunder force derived from pressure in the charging chamber.

2. An impact ram according to claim 1 in which the opening in theplunger adjacent said first end is tapered narrowing toward said firstend, and in which the piston includes a reduced portion adapted to entersaid open ing so as to gradually reduce the lateral separation betweenthem, thus decelerating the plungers motion away from the first end.

3. An impact ram according to claim 2 in which the piston has a seat ona portion thereof which is adapted to contact the plunger, and which inthis position holds the piston so that a spacing exists between thepiston and the plunger in fluid communication with the charging port.

4. An impact ram according to claim 1 which the said seals areconcentric, cylindrical, and have substaniially equal diameters so as toform a sliding seal.

5. An impact ram according to claim 1 in which a stop shoulder is formedin the plunger cylinder, spaced from the open end for limiting thetravel of the piston away from said first end.

6. An impact ram according to claim 5 in which the opening in theplunger adjacent said first end is tapered, narrowing toward said firstend, and in which the piston includes a reduced portion adapted to entersaid opening so as to gradually reduce the lateral separation betweenthem, thus decelerating the plungers motion away from the first end.

7. An impact ram according to claim 1 in which the triggering meanscomprises a mechanical element adapted to force the plunger away fromsaid first end.

S. An impact ram according to claim 1 in which the triggering meanscomprises a triggering port opening into the triggering chamber, and aconduit adapted to supply fluid under pressure thereto.

9. An impact ram according to claim 1 in which the conduitry comprises areturn port opening through the body into the return chamber foradmitting fluid under pressure into the return chamber; a charging portopening into the charging chamber for admitting fluid under pressurethereto; and a valve adapted to connect both of said ports to a sourceof pressure in one condition, and to connect the return port to pressureand the charging port to exhaust in another condition.

10. An impact ram according to claim 1 in which the conduitry comprisesa return port opening through the body into the return chamber, and acharging port opening through the wall of the plunger andinterconnecting the return and charging ports therethrough.

11. An impact ram according to claim 1 in which the piston has a seat ona portion thereof which is adapted to contact the plunger, and which inthis position holds the piston so that a spacing exists between thepiston and the plunger in fluid communication with the charging port.

12. An impact ram according to claim 1 in which delay means isinterposed between the plunger and the piston to delay the return of thepiston toward the open end of the plunger and thereby delay thedeceleration of the plunger.

13. An impact ram according to claim 12 in which the delay meanscomprises a pair of axially-extending surfaces on the piston, one havinga greater and the other a lesser lateral dimension, and a meteringsurface on the inside of the plunger spaced laterally from the surfacehaving the greater lateral dimension, whereby to form a metering orificewhen they are axially aligned, and to form a larger by-pass when axiallyaligned with the surface of lesser lateral dimension.

14. An impact arm according to claim 10 in which delay means isinterposed between the plunger and the piston to delay the return of thepiston toward the open end of the plunger and thereby delay thedeceleration of the plunger.

15. An impact ram according to claim 14 in which the delay meanscomprises a pair of axially-extending surfaces on the piston, one havinga greater and the other a lesser lateral dimension, and a meteringsurface on the inside of the plunger spaced laterally from the surfacehaving the greater lateral dimension, whereby to form a metering orificewhen they are axially aligned, and to form a larger by-pass when axiallyaligned with the surface of lesser lateral dimension.

16. An impact ram according to claim 10 in which the piston has a seaton a portion thereof which is adapted to contact the plunger, and whichin this position holds the piston so that a spacing exists between thepiston and the plunger in fluid communication with the charging port.

References Cited UNITED STATES PATENTS 3,103,136 9/1963 Bollar 60-523,158,048 11/1964 Bollar 928 3,205,790 9/1965 Bollar 73l2 3,267,6778/1966 Bollar 6054.5 2,679,827 6/1954 Perdue 91-4 2,829,498 4/1958Ferguson 6054.5 3,105,414- 10/1963 Cvjetkovic et al. 9l4l7 3,200,7158/1965 Ottestad 91392 3,202,059 8/1965 Ottestad et a1 91-392 3,266,8698/1966 Dengler 925l 3,311,049 3/1967 Hugi 91173 MARTIN P. SCHWADRON,Primary Examiner.

PAUL E. MASLOUSKY, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,363,513 January 16 1968 Jack B. Ottestad It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 2 line 38 for "Fuild" read Fluid line 46,

for "ends" read end line 54, for "trigger" read triggering column 8,line 55, for "selectable" read selectible column 10, line 15, after"tapered" insert a comma; line 27 after "1" insert in column 11 line 6,for "arm" read ram Signed and sealed this 25th day of February 1969.

(SEAL) Attest:

Edward M. Fletcher, J r. EDWARD J. BRENNER Attesting OfficerCommissioner of Patents

